He has a URI and has difficulties drinking? Try this.... Get Chocolate Ensure (it is thicker, higher viscosity, which is easier for him to drink and not choke on, as well as a great nutritional aide and Baytril bitterness masker) and give very small amounts repeatedly for as long as he drinks it. And here's the trick.... Dont use a flat bottomed dish, such as a lid or common food dish, but rather a rounded bottom bowl, such as big spoon. A tablespoon will do just fine, it allows him to lick from the edges, which gives him assurance that he doesn't lick too much and accidentally swallow too much, or try to, and end up choking. He will lick from the very edge until it is nearly gone and then finish it up licking in the center, where the remaining Ensure is. Repeat as many times as necessary. If he refused the Baytril you can give it to him in tiny increments, such as 0.02ml doses that you can keep giving with each new spoonful of Ensure, until you add all the spoonfuls up to the correct dose. If he gets extremely dehydrated you can give wet foods such as frozen peas and corn (he will probably choose a preference, which is fine, but sometimes when they get really bad they will benefit from you shelling the peas for him, as he can have a hard time with it himself due to the eating/breathing relationship (basically it's one or the other at this stage of the illness), so be understanding and prepared to help him in ways you never imagined. Lastly, if his dehydrated becomes critical, you can give subcutaneous injections of saline solution to hydrate, with a dose of about 3ml every 6 hours, in a different site each time, such as large muscular areas (thighs, rump, front upper legs, etc. with extremities being the easiest for novices. I just use a short needle insulin syringe and check to make sure you did not hit a vein, although I don't see the reasoning for why that's not good, but it's recommended to be subcutaneous, so that's the method This is for emergencies in which your rat will not drink. I've only had to do it once, overnight while I waited for my vet to open at 8am to have him humanely helped across the bridge. He wouldn't even eat his shelled peas, or his whipped cream, and was open mouth gasping for oxygen, so it was very serious and I was not going to let him suffer through a suffocation. I've had it happen twice, once to my exes first pet rat, and once to one of my rescues who was absolutely fine until suddenly, one day, he wasn't. He passed in my arms the next day (a Sunday) as I was on the phone with an emergency 24 hour vet. I knew he was going to not make it when he became frantic and I couldn't soothe him and calm him down. He ran erratically back and forth on me frantically looking for relief from his suffocating and wouldn't be consoled, which escalated his situation. It was absolutely the worst moment you'll ever know with rat caretaking. If only he hadn't hidden his illness so damn well. I check all my rats weekly for breathing sounds, lumps, infections, grooming abilities, etc. He never had a single tiny symptom, and that is normal behavior for rats to hide their injuries and illnesses, but he was exceptionally good at it, which was his ultimate downfall. So terribly sad. Anyway, I'm rambling on now so I will end with a little prayer for your rattie. I hope he gets well soon.